I was running 3S 5000 mah packs but flight times were 7-10 minutes for some reason. (maybe to cold) so I purchased a 3S 8400mah pack for a good 15 minute flight. I'm pulling about 453mah a minute with the current setup.

I am STILL getting the toilet bowl effect once in a while. Sometimes it just has a mind of it's own and wants to bank hard right. I am forced to leave GPS mode and go into ATTI mode for a few minutes until I can hover in place and then switch back to GPS mode.

I have no idea what's causing this issue because it's random and it's 50-100 feet in the air, so there can't be much interference around. I was hovering over a friends house and it was rocking back and forth like the gains were to high...not sure what's causing this either since I haven't changed anything and it's been fine for the last 10 flights. But while jittering, it just pulled 10-15 degrees hard right, back, left, forward, etc...into a large toilet bowl effect (TBE) at a faster and faster pace.

If I ever decide to give FPV a try, this is going to be a deal breaker.

I just tried my RTH this past weekend and it was a bit scary! I hooked up the lipo in the middle of an open field with nothing but me around it. It locked on to the GPS in about 30 seconds. Took off and flew out about 60 feet. Went from ati to RTH, quad leveled and climbed to around 60', turned quickly around and started back. Once it got to about 20 feet from where I took off it began to toilet bowl around me and started to gain a bit of speed so I took over and landed. I tried it a couple of more times with the same results. What am I doing wrong?

If you find out...please let me know because I'm having the same problem!

The one thing I haven't tried is actually calculating the EXACT CG location for the cm measurements within the naza software for the GPS. Mine are "estimated" based on the physical center of the hex...but I can't image that a slight error would cause the TBE.

Sometimes, I've been able to recalibrate the compass and that has reduced or temporarily eliminated the TBE. Also, do you have your GPS rotated to account for the delta between magnetic north and true north? In Buffalo, NY, it's about 10 degrees counter clockwise.

I think Sacramento, CA, is about 14 degrees to the right...or clockwise.

If you find out...please let me know because I'm having the same problem!

The one thing I haven't tried is actually calculating the EXACT CG location for the cm measurements within the naza software for the GPS. Mine are "estimated" based on the physical center of the hex...but I can't image that a slight error would cause the TBE.

Sometimes, I've been able to recalibrate the compass and that has reduced or temporarily eliminated the TBE. Also, do you have your GPS rotated to account for the delta between magnetic north and true north? In Buffalo, NY, it's about 10 degrees counter clockwise.

I think Sacramento, CA, is about 14 degrees to the right...or clockwise.

Thanks for the info! I know this is a stupid question but how would I adjust for that? I too am trying to figure this out!

The arrow on the GPS unit is suppose to point directly forward initially. That arrow is the North point on the built in compass...which oddly enough is also the location where the cable comes out of the GPS unit. (seems backwards)

Anyway, I would start by making that point directly forward and testing it in flight. While in GPS mode fly a straight line. If it starts to drift left, rotate the GPS to the right. Also, visa versa. Once you have it exactly right, it should be able to track a straight line all day long.

That is how I have mine set now. I do notice that when I switch into GPS that my tail drops a bit and then levels out. Think I might try settin the CG mark a bit further forward in the programming and see if that helps. I will keep you posted and thanks for the help!

I went back out today after investing in 6 new perfectly balanced Carbon Fiber blades. The vibration is GONE...but the TBE is even worse now. It's really starting to annoy me that I can't figure out what the issue is.

In ATT mode, it hovers in place pretty well with zero wind. As soon as I switch to GPS mode, it banks (usually left and then back) into a steeper and steeper bank until it's a good 25-30 degrees of bank and going VERY fast. At this point, I have no choice but to remove GPS mode or face an imminent crash. I'd really like to figure out why it works sometimes and not others.

Problem "MAY" be solved. I went back and found my actual CG on the Z axis and I was 2cm off. I also realized that, even though the battery was directly above the NAZA, the CG was slightly off center...so the NAZA was about 1-2cm away from the CG. I moved the battery over to the right and got the hexacopter to balance directly over the NAZA and now it works perfectly. I'm not sure if it was the CG balancing or the 2cm change in the software, but I'm not going to play around with it as long as it continues to work.

So far, I've had a 15 minute flight and an 18 minute flight with excellent GPS locking. I can go full speed (about 35-40mph) and then immediately come to a stop with zero TBE. I went up about 56 meters and it just stayed in place for about a minute before I lowered it. Also, the bouncing on landing while in failsafe mode is completely eliminated as well. Not sure if it's because of the CG change, change to the NAZA GPS values, or just the new CF props, but I'm very impressed with this setup now that it's working correctly.

For anyone following this thread...the issue was my CG being off by about a half inch. Once I moved my heavy battery to the right, the CG was dead center over the MC and the TBE is completely gone. I've had about 15 flights since then without a single issue. :-)

Problem "MAY" be solved. I went back and found my actual CG on the Z axis and I was 2cm off. I also realized that, even though the battery was directly above the NAZA, the CG was slightly off center...so the NAZA was about 1-2cm away from the CG. I moved the battery over to the right and got the hexacopter to balance directly over the NAZA and now it works perfectly. I'm not sure if it was the CG balancing or the 2cm change in the software, but I'm not going to play around with it as long as it continues to work.

So far, I've had a 15 minute flight and an 18 minute flight with excellent GPS locking. I can go full speed (about 35-40mph) and then immediately come to a stop with zero TBE. I went up about 56 meters and it just stayed in place for about a minute before I lowered it. Also, the bouncing on landing while in failsafe mode is completely eliminated as well. Not sure if it's because of the CG change, change to the NAZA GPS values, or just the new CF props, but I'm very impressed with this setup now that it's working correctly.

What props did you end up getting? My RTH is getting better but still need to dial in the CG. Getting closer!

CG is apparently VERY important. It was off by 1/2" and that's what caused me months of issues. I'm using Gemfan carbon fiber 10x4.5 props and the vibration is very low.

The Gemfan nylon fiber props were horribly off balance at the prop hub which causes serious vibration. I spent a good hour trying to balance them and finally tossed them out once I gave these cf props a try.

CG is apparently VERY important. It was off by 1/2" and that's what caused me months of issues. I'm using Gemfan carbon fiber 10x4.5 props and the vibration is very low.

The Gemfan nylon fiber props were horribly off balance at the prop hub which causes serious vibration. I spent a good hour trying to balance them and finally tossed them out once I gave these cf props a try.

Good to hear on the CF Gemfan props as I just ordered a set. How exactly do you figure out the CG? I assumed that the X axis is the front to back and Y/Z are left to right?